Font type and size

Hi,

since my website is a news blog, and I work with a lot of external contributors, I use this plugin very heavily.

The problem comes with font and other stylings.

I must work with html, since some of posts contains pictures in the middle of the post, and anyway I need some basic styling which comes by the contributors (such as bold or break lines).
The problem is that each contributors sends contents with different styles, especially different font types and sizes.
Is there a way for me too keep the default css of my theme for fonts, and still keeping other html tags that I get from the contributors?

Thank you

http://wordpress.org/extend/plugins/postie/